Climate change is having a significant impact on the biology and ecology of fish stocks and aquaculture species and will affect the productivity within seafood supply chains in the future. The challenges are further amplified when actors within the fisheries and aquaculture sectors have very different ideas and assumptions about climate change and what risks and opportunities they entail. In order to address the challenges of climate change, several countries have developed national adaptation plans. However, fisheries and aquaculture are rarely included in these plans, resulting in a general lack of documented adaptation strategies within these sectors in most countries. This paper introduces guidelines for the development of climate adaptation plans (CAPs) within fisheries and aquaculture, applying a co-creation approach that requires the participation of scientists, industry representatives, policymakers, and other relevant stakeholders. The objective is to provide a stepwise approach to facilitate and enable stakeholders to plan strategies toward climate adaptation. The guidelines are based on practical experience and include a three-step process: (1) assessment of risks and opportunities; (2) identification of adaptation measures, and (3) operationalization of CAPs. The three-step process is also part of a larger cycle, including implementation, monitoring, and evaluation, again generating iterative feedback loops over time. Lessons learned are discussed, and we highlight the advantages and challenges of developing CAPs. While the guidelines are designed for and tested within fisheries and aquaculture systems, the CAP approach is also employable for other natural resource-based systems.